Fish, like birds, migrate; their method and success in doing so, however, differs vastly. Birds typically fly south for the winter, whereas fish, both adult and juvenile, may migrate either upstream or downstream. Further, while birds flying through the air often reach their migratory destination unhindered, migrating fish today encounter an ever-growing number of man-made obstacles blocking their traditional migrating pathways. For example, the lower Columbia River, a well known migratory pathway for salmon, steelhead and sturgeon, has five dams between the Pacific Ocean and the mouth of the Snake River. Similarly, the Snake River, also a traditional fish migratory pathway, has four hydroelectric facilities on the first 110 miles of river.
The numerous dams and hydroelectric facilities that block traditional fish migratory pathways throughout the Unites States, as well as other countries, present a continuing threat to the existence of numerous fish species. As a prime example, on the Pacific coast today, salmon and steelhead face the danger of extinction, due in part to the fact the juvenile fish mortality rate for those passing through or over man-made obstructions can be as high as 30 percent. On the Atlantic coast, striped bass, eels and Atlantic salmon face a similar plight.
Declining anadromous fish stocks have prompted many studies to determine the causes of increased fish mortality rates, in particular, the enormous concentrated effort led by the U.S. Army Corps of Engineers during the 1990s. At the direction of the National Marine Fisheries Service, the Corps of Engineers, Bonneville Power Administration, Bureau of Reclamation, Environmental Protection Agency, U.S. Fish and Wildlife Service, and various agencies of the States of Idaho, Oregon and Washington cooperated in an intensive study of the Snake River. The study resulted in information on salmon and steelhead migratory patterns and problems.
The primary problem is that natural and manmade obstructions, such as dams and locks, have prevented upstream and/or downstream migration of anadromous and migratory fish. Recent efforts to solve this problem have produced mixed results.
A hydroelectric facility commonly consists of a dam wherein a large quantity of the river water is stored temporarily and passes through hydroelectric generating turbines and the like in a manner that is known to those skilled in the art. It has been shown that the mortality rate for juvenile fish passing through or over such facilities is from 10-30 percent. Thus, in passing through a series of hydroelectric facilities the number of fish surviving to reach the ocean is significantly reduced compared to the number that started the journey.
Recent efforts to solve this problem include the use of collection systems and then transportation by tank truck or barge to the ocean. The use of behavioral guidance systems, trucking and barging of smolts has not been as effective as hoped. Other efforts have been made by the use of conduits around the dam to allow fish to pass. These efforts have produced marginal results as is witnessed by the continued decline of returning fish causing them to be listed as endangered.
A similar problem exists with the upstream migration of adult fish to their natal or spawning areas. The existing method of using fish ladders located at the tailrace or by the turbine discharge area has had marginal success. The upstream migrating adults enter this area of turbulence and become confused. They have difficulty locating the fish ladders"" current and thus fail to negotiate the dam. Those that do find the ladders risk injury or suffer from exhaustion and are in a weakened condition if they reach a spawning area.
Another problem for upstream migrating adult fish is the absence or lack of suitable spawning areas. Presently, a large percentage of adult fish are captured at hatchery sites and stripped of their eggs manually. These hatchery-raised juvenile fish are less likely to have the survival skills necessary to survive downstream migration.
The problems that dams and other hydroelectrical facilities pose by blocking migrating fish has long been recognized, and the need to provide an effective passage for migratory and anadromous fish has been recognized for some time, as well. In the past there have been attempts to utilize fish ladders or conduits for diverting fish both upstream and downstream around hydroelectric dams or the like for the intended purpose of attempting to protect fish from passing through hydroelectric turbines and the like where they are generally destroyed in large numbers. None of the heretofore devised or conceived methods have included a method and system of creating an artificial condition that in essence simulates, duplicates or replicates the natural stream or river from which migrating fish enter hydroelectric dam reservoirs. Further, such prior attempts have in no manner encompassed a variety of techniques to provide a natural-like surface stream or river condition that induces rather than forces fish to safely traverse around the dam area and to discharge them into the natural stream below the dam.
Several attempts at addressing and solving these problems have heretofore been offered, such as fish ladders and mechanical, conduit by-pass systems and other mechanical devises, of either limited scope and effectiveness or requiring a high degree of maintenance, e.g., U.S. Pat. No. 3,377,805 (1968), U.S. Pat No. 3,962,876 (1976), U.S. Pat. No. 4,260,286 (1981), U.S. Pat. No. 4,437,431 (1984), U.S. Pat. No. 4,629,361 (1986), U.S. Pat. No. 4,904,114 (1990) and U.S. Pat. No. 5,161,913 (1992). U.S. Pat No. 3,377,805 to Warner (1968) discloses a fish elevator to raise and lower fish around an obstruction. A similar attempt was proposed by Warner and Schjelderup, U.S. Pat. No. 4,904,114. U.S. Pat. No. 3,962,876 to Phillips (1976) discloses a simple fishway. U.S. Pat. No. 4,437,431 (Koch), U.S. Pat. No. 4,629,361 (Zimmerman) and also U.S. Pat. No. 5,161,913 (Boylan) utilize conduit systems.
Each of the attempted solutions in the above patents, however, suffers from one or more of the following disadvantages: it requires costly man-made mechanical devices, artificial lighting or pumps; it is a complex system requiring high maintenance; it requires artificial syphoning and oxygenating systems; it requires placement of a device at the face, in the reservoir or within the tailrace of a dam limiting its effectiveness; it does not account for varying adult and juvenile fish habits or differences in upstream and downstream migration; the draw of the turbine intake competes for juvenile fish and the turbine discharge confuses the adult fish; it lacks adequate means to attract and entice fish to utilize the by-pass or throughway system; it does not effectively solve the problem of a dark or enclosed passageway discouraging fish to enter, it does not prevent darkening of a fish passageway, resulting from silt or algae accumulation to a translucent conduit, thereby discouraging fish; it is cost-prohibitive for any, some or all of the foregoing reasons; and it is not readily adaptable to a wide variety of fish species"" migratory habits. Further, none of the prior solutions offered incorporate a method and system in and to which fish would most naturally adapt and likely thrivexe2x80x94that of a simulated, duplicated or replicated natural stream or river similar to that in which migrating fish travel, prior to entering any area of man-made stream or river obstruction, such as a reservoir to a hydroelectric facility. Moreover, the prior solutions do not encompass techniques to provide a natural-like surface stream or river condition that induces, rather than forces, fish to safely traverse around the obstructed area and discharge the fish into the natural stream below the obstruction. In these respects, there is thus no prior art relating to the present invention.
Because of the disadvantages of the existing methods and systems designed to allow migrating fish to bypass or pass through man-made obstructions and because of the continuing decline of fish populations, the need for a natural feature based method and system is paramount. Such a method and system offers several advantages over existing methods and systems: it is economical, since it requires minimal maintenance once in place; it can be readily utilized for both adult and juvenile fish migrating either upstream or downstream; because it mimics the waterway from which the migrating fish come, by its nature it will entice fish; and it is flexible enough to use with any migrating species.
This invention is a method and system for providing upstream and downstream migrating fish a means for bypassing man-made obstructions, such as hydroelectric facilities, and natural obstructions such as waterfalls or rapids, by simulating or replicating the natural stream conditions to which the fish are accustomed and diverting them through the simulated or replicated condition around the obstructions. The method and system are further characterized by utilizing features that appeal to the natural migratory tendencies and attract the fish to and entice them to use the desired channel to bypass the obstruction to their migration This method and system is more particularly directed to the creation of an artificial stream or river inlet in the relatively quiet waters behind the obstruction and in the downstream migratory path of the fish, and thus simulating or replicating what would be the natural course for the fish to take together with channeling them into a simulated or replicated river or stream; around the obstruction and into the natural river course below the obstruction at a great enough distance to attract upstream migratory fish before they reach the tailrace or base of the obstruction.
My invention is an effort to provide a feasible, cost-effective, natural-like solution to the problem of natural and man-made obstructions, such as dams and locks, preventing upstream or downstream migration of anadromous and migratory fish. Though this invention focuses on the needs of salmon and steelhead, it is readily adaptable to other migratory species.
It is an object of this invention to provide a river-like channel to convey juvenile and adult fish around dams and obstructions.
Another object of this invention is to provide natural-like features for the migrating fish and deceive them into believing they are in a river.
Another object of this invention is to provide for a food source so fish will migrate at their own natural pace.
A further object of this invention is to create an environment that allows juvenile fish to prepare for adulthood in a natural manner.
Past attempts to utilize fish ladders, or conduits for diverting fish both upstream and downstream around hydroelectric dams or the like for the intended purpose of attempting to protect fish from passing through hydroelectric turbines and the like have not included this invention""s method of creating an artificial condition which in essence simulates, duplicates or replicates the natural stream or river from which they entered the hydroelectric dam reservoir. Further, such prior attempts have in no manner encompassed a variety of techniques to provide a natural-like surface stream or river condition which induces rather than forces fish to safely traverse around the dam area and to discharge them into the natural stream below the dam. In this respect it can be considered that there is no prior art whatsoever relating to the present invention.